In the game of bowling, heavy spherical balls are rolled down a lawn or an indoor alley and targeted at a set of wooden clubs called pins, usually a triangularly positioned set of ten pins (called tenpins) standing upright on a skittle alley at the rear end of the bowling alley, in an attempt to knock them down. Experts are often able to strike all tenpins in a single ball shot, but laymen will usually be able to knock down only a fraction of the total number of pins. A player may, according to bowling game rules, try at least a second time to knock down the pins that remain upstanding on the skittle alley. In order to ensure that the knocked down pins from the first ball shot do not interfere with those unstruck pins that remain upright on the skittle alley, it is necessary to remove the knocked down pins from the skittle alley area, after each ball throw.
Known systems for segregating the knocked down pins from the unstruck pins, consist of a large perforated partition, extending horizontally above the skittle alley and movable vertically thereabout through power means. After each ball throw, the partition is lowered, to engage and temporarily secure the heads of the pins that remain in upstanding position, and then lifted, bringing therewith the pins. The knocked down pins, which were not captured by the moving partition, will be then cleared from the skittle alley by a mechanical means, for example a horizontally sliding rake skimming the surface of the skittle alley toward a rear skitte pit, for discharge of the knocked down pin therein. The partition will then be lowered once again to release the remaining pins in their original upstanding position in triangular arrangement.
Such known systems are not efficient, because of the complexity of the pin removing and setting system.